I'm looking to build up a rear wheel with a 3 speed internal hub for use on a track style frame (120mm spacing horizontal track fork ends). I have a few questions that maybe some of you can help me with.

1. Which brand (nexus, sturmey archer, sram) has models that will fit into 120mm rear spacing?
2. What hub can take the most abuse. I'm 6'1" 200 lbs so I need a sturdy hub.
3. I am looking at the sram imotion speed with a coaster brake. Will this hub work on my frame? I cannot find any specs on it.